"A pathologist from the International Agency for Research on Cancer once told me that the biggest mistake we ever made was attaching the word 'carcinoma' to DCIS," Welch says.
When it comes to DCIS, the mammogram delivers information without true understanding.
The pathologists looked at an average of two hundred and seventy-five samples of breast tissue in each case, and found some evidence of cancer — usually DCIS — in nearly forty per cent of the women.
About fifty thousand new cases are now found every year in the United States, and virtually every DCIS lesion detected by mammography is promptly removed.
In the past couple of decades, as more and more people have received regular breast X-rays and the resolution of mammography has increased, diagnoses of DCIS have soared.
The disturbing thing about DCIS, of course, is that our approach to this tumor seems like a textbook example of how the battle against cancer is supposed to work.
That's why some doctors feel that we have no choice but to treat every DCIS as life-threatening, and in thirty per cent of cases that means a mastectomy, and in another thirty-five per cent it means a lumpectomy and radiation.
There is no definitive answer, and it's all but impossible to tell, simply by looking at a mammogram, whether a given DCIS tumor is among those lesions which will grow out from the duct or part of the majority that will never amount to anything.
"Almost half a million women have been diagnosed and treated for DCIS since the early nineteen-eighties — a diagnosis virtually unknown before then," Welch writes in his new book, "Should I Be Tested for Cancer?," a brilliant account of the statistical and medical uncertainties surrounding cancer screening.
But what has the targeting and destruction of DCIS meant for the battle against breast cancer?
